. Bulletins of American paleontology. Oldest Crinoids: Guensburg and Sprinkle 21 Order 'DIPLOBATHRIDA Moore and Laudon, 1943 Discussion.âDiplobathrid camerates are defined by a single trait, a dicyclic cup, that we rind to be incon- sistent early in crinoid phylogeny (see Primary Cup Plate Homologies). Family RETEOCRINIDAE Wachsmuth and Springer, 1885 Emended diagnosis.âDicyclic camerate crinoids with heavy cup plate ridges forming a trusswork, deep- ly depressed pockets or fenesta between ridges and in interray regions, infrabasals overhanging stem, radials separated all around, wide posterio
. Bulletins of American paleontology. Oldest Crinoids: Guensburg and Sprinkle 21 Order 'DIPLOBATHRIDA Moore and Laudon, 1943 Discussion.âDiplobathrid camerates are defined by a single trait, a dicyclic cup, that we rind to be incon- sistent early in crinoid phylogeny (see Primary Cup Plate Homologies). Family RETEOCRINIDAE Wachsmuth and Springer, 1885 Emended diagnosis.âDicyclic camerate crinoids with heavy cup plate ridges forming a trusswork, deep- ly depressed pockets or fenesta between ridges and in interray regions, infrabasals overhanging stem, radials separated all around, wide posterior interray, isoto- mously branched nonpinnulate arms, brachials with lateral protuberances, sac-like tegmen consisting of plates similar to interbrachials. not extending beyond arm tips, and long thick stem with thin pentameric to holomeric wafer-like columnals. Genus CNEMECRINUS, new genus Type species.âCnemecrinus fillmorensis Guens- burg and Sprinkle, new species. Diagnosis.âReteocrinids with wide conical cup, thinly plated pockets between pronounced cup plate ridging, interbrachial areas occupied by tesselate stel- late plates, single large interbrachial contacting basals, CD interray wider than others, merging with sac-like tegmen (but lacking a sagittal anal ray-like ridge); arms nonpinnulate, isotomously branched at least four times, free Brr with rounded lateral protuberances; stem long, rounded pentalobate near crown, hetero- morphic, tapering distally, cryptopentameric. Occurrence.âLower Ordovician. western Utah, U. S. A. Etymology.âFrom the Greek kneme, spoke of a wheel, in reference to the heavy radiating ridges of cup plates. Discussion.âCnemecrinus n. gen. has cup plating similar to other dicyclic camerates. The sac-like teg- men. stellate lower cup plates, large interbrachial ar- eas, fixed lower arms up through the primibrachs or low in the secundibrachs, the lower primibrachs strongly articulated with adjacent interbrachials, long nonpinnulate arms, and
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